Results 1 to 22 of 22

Thread: Head upgrade

  1. #1
    Join Date
    Aug 2010
    Location
    West Nyack, New York
    Posts
    902
    My Cars
    1986 635csi & 1998 740i

    Head upgrade

    1986 CSi stock M30 engine 150,000 miles, Miller MAF and chip. Engine never opened in 32 years.

    Blew the head gasket @ Watkins Glen. Ran really great until turn 11.

    While I have it repaired, I was thinking of a mild upgrade.

    Depending on basic worn out head parts that need replacing, what would be the

    recommendations to up the hp for more ump. Not looking for massive rebuild,

    just to gain something while I'm in there. I don't know what hp I'm looking for.

    Don't want to touch the bottom end at all, Compression was all above 155 last time checked.

    No water in the oil, I caught the problem early. So if suggestions could give hp gain, that will help me

    make my decision. To go from 182 hp to 200 I would have to do what?

    To 220 then it would take this. Or to 240 it would be that, or the best you could do

    is this hp and would need these parts as an upgrade. I'll assume I'll have to get a Miller War Chip for the MAF

    and program accordingly.

    If the B34 head is still good, I'd like to use it. What could I do with it?

    If not I guess it would be a B35 head. Or maybe, I'll have to get a B35 head to make upgrade in hp easier.

    Complete novice when it comes to this. Upgrading brakes and suspension was easy for me.

    This stuff is out of my realm of knowledge.

    I'm going to post on Bimmerforums 5 series and Big Coupe as they will also have much more experience than me.

    I've searched the posts on this subject and now I'm more confused.

    Want to thank you all for any and all input.

    Bob V
    Last edited by 1986series6; 06-13-2018 at 07:42 PM.

  2. #2
    Join Date
    Apr 2008
    Location
    Scottsdale, Arizona
    Posts
    4,452
    My Cars
    81 euro 635, 4.4 X5
    B35 head is great as it has larger valves. Problem is the combustion chambers are larger and you will lose compression. Milling the head can cure that. A mild cam maybe?. From there it depends on cylinder wear, timing chain wear, chain guides etc.
    Don or anyone else????
    81 Euro undergoing total nut and bolt restoration
    pictures at: flickr.com/photos/bertsphotos

  3. #3
    Join Date
    Sep 2010
    Location
    Hagerstown,MD
    Posts
    945
    My Cars
    1984 Euro 635
    Bob, How much money do you want to spend?

    In addition to having larger intake valves, the B35 intake flows a bit better. Ireland Engineering has pretty good camshaft options (282/284?). A true "cold" air intake would compliment the larger intake/valve setup on the B35 head. THEN, you have to look at getting that aditional air/fuel out the backside. Headers and a free flowing exhaust would address that. I would think 200-225 hp could be realistic.
    '84 Euro 635
    '88 M6 (Gone but not forgotten)

  4. #4
    Join Date
    Feb 2008
    Location
    SoCal
    Posts
    597
    My Cars
    '85 635CSi, '87 535is
    Here's some M30 buildup info by Rob Anderson, circa 2001. Scroll down to "Hi Power M30":

    http://www.m535i.org/officers/ra/article.html#motor


    If you're not upping the compression (which gets expensive, as you know) then you're rather limited on what you can do. I'd use a B35 cam (slightly more lift/duration than the B34 cam, but will work OK with the stock CR), have your B34 head ported, headers, free flow exhaust (meaning no cat, with free flow muffler), and a lower diff ratio such as a 3.91. Having the intake manifold extrude-honed gains about 10 HP @ 5500 rpm according to my old Dinan literature, but it's not very cost effective (last I checked was $800).
    Last edited by LarryM; 06-13-2018 at 09:25 PM.

  5. #5
    Join Date
    Aug 2008
    Location
    Sydney Australa
    Posts
    2,164
    My Cars
    1x633, 1x E3 2 DR Racer
    There is so much you can do for smaller dollars. Try;

    1. B35 head and deck it to increase compression. You should deck any new head anyway as more than likely it is not perfectly flat. If you have a stock low compression B34 head you should have room to deck to increase compression and still retain valve clearances. Or, Deck your old head 1mm to 2mm. Use a thinner MLS gasket as well. Measure current compressed thickness and then decide on something thinner.
    2. Mild cam upgrade.
    3. 2.5 inch exhaust.
    4. Big bore throttle body. Use the Land Rover Discover II 2003 V8 throttle body.
    5. Extractors.

    Anything else will start to really lead into the dollars. The above should easily give you 220hp plus. Maybe even up to 240hp.
    1977 633 CSi RHD Euro. S38B38 3.8L M5 Transplant. 5 Speed Getrag Dogleg. 3.45 LSD. 390hp, 331lb/ft
    1971 3.0CS E3 2dr Alpina Special Coupe Racer, 300hp, 277lb/ft

  6. #6
    Join Date
    Jul 2008
    Location
    Boston, Ma
    Posts
    1,369
    My Cars
    86 635,72 E3, 88M6,73 E9
    or....................you could buy my M6. Kidding not for sale. Good luck with this Bob. Always an iteration process when you start an upgrade.
    Rob E3

  7. #7
    Join Date
    Sep 2009
    Location
    Denver, Colorado
    Posts
    2,862
    My Cars
    1985 535i, 1980 635CSi
    Best bang for your buck would be a valve job, 3 angle valve grind. Otherwise, you can swap to the better flowing B35 head but it lowers compression but you are no better off since you are still NA.


    You could change the cam for a bit better high rpm flow, but there isn't a lot to do that is a good bang for the buck IMO.

  8. #8
    Join Date
    Aug 2010
    Location
    West Nyack, New York
    Posts
    902
    My Cars
    1986 635csi & 1998 740i
    OK tschultz

    I give up, this means? "but you are no better off since you are still NA."

    Rob E3

    Hope I can get er done by "Idiotfest"
    Last edited by 1986series6; 06-14-2018 at 02:28 PM.

  9. #9
    Join Date
    Sep 2009
    Location
    Denver, Colorado
    Posts
    2,862
    My Cars
    1985 535i, 1980 635CSi
    Quote Originally Posted by 1986series6 View Post
    OK tschultz

    I give up, this means? "but you are no better off since you are still NA."

    Rob E3

    Hope I can get er done by "Idiotfest"
    Naturally aspirated.

    If it was me, I would regrind the valves since the head will be off anyway. That will give you some better flow. Then, decide if you want to buy a shrick or other performance cam at the same time. It just won't be a huge difference, but a small one if you want better high rpm performance at the sacrifice of low rpm torque.

  10. #10
    Join Date
    Aug 2010
    Location
    West Nyack, New York
    Posts
    902
    My Cars
    1986 635csi & 1998 740i
    Oh my!!! I should have known NA. Thanks for not bustin' my chops on that one.

  11. #11
    Join Date
    May 2013
    Location
    Moultrie, Ga. USA
    Posts
    165
    My Cars
    87 635CSi, 88 635CSi,
    Euro B34 head and cams? I wouldn't want to sacrifice any low end torque, in fact that's exactly where I'd love to have an increase. But it would probably be at the expense of some upper rpm's...

  12. #12
    Join Date
    Aug 2008
    Location
    Sydney Australa
    Posts
    2,164
    My Cars
    1x633, 1x E3 2 DR Racer
    If you want to increase torque then increase capacity and flow. More flow means more bang. You can go to a 294 degree catcam before lowdown torque is affected. Once you hit the 300's in any cam hp will be pushed up the rev range.
    1977 633 CSi RHD Euro. S38B38 3.8L M5 Transplant. 5 Speed Getrag Dogleg. 3.45 LSD. 390hp, 331lb/ft
    1971 3.0CS E3 2dr Alpina Special Coupe Racer, 300hp, 277lb/ft

  13. #13
    Join Date
    Dec 2005
    Location
    Melbourne, Australia
    Posts
    1,794
    My Cars
    M3evo-Twin Screw/M635csi
    On 8:1 compression swapping cams etc will be counter productive. If not changing pistons perhaps use a thin 027’ mls head gasket (std is 070’) and then take another skim of the head to get around c/ 9.5:1 comp, then upgrading cams etc makes sense. Will need to consider fly cutting pistons to ensure piston to valve clearance is ok. By the time u do all this tho some high comp pistons may be what u really should have gone for in the first place. Good luck, but with out good comp, power upgrade efforts may only lead to disappointment.

    Depending on cam agressiveness and available fuel octane comp should be in the 9.5 to as much as 11.3:1. If you are targeting peak power at any more than 5500, u will need either doce Weber’s or some other form of individual throttle bodies. If going down this path you could build a streetable m30 that would make a mess of the std s38!!!
    BMWs
    74 2002 2.3ltr
    84 E24 M635csi
    86 E23 735i
    94 E34 540i/6 SC 14psi
    97 E36 M3 euro SC

    OTHERS
    02 Landrover D2 td5, 08 Holden Ute 6.0, 11 Audi S5 APR


  14. #14
    Join Date
    Mar 2009
    Location
    Melbourne, Victoria, Australia
    Posts
    244
    My Cars
    1986 BMw 635 CSi
    Before you go any further, as GazM3 has stated, so much depends upon your compression. Is your engine the low comp 8:1 version, or the higher compression euro spec?

    The higher comp engine will respond much better to other improvements, such as a more aggressive cam, maybe larger valves etc. and chip upgrades. But the low comp 8:1 is really limited, and will actually suffer with some "upgrades". I also had a blown head gasket on my 8:1 recently and was in the same position as you now, looking at what simple improvements could be made. Everything led to getting higher compression. One way is to upgrade to euro spec B34, ie higher compression pistons, and euro cam, (or stock B35 cam which is the same as the B34 Euro spec) and the same head - I was not willing to spend the considerable extra $, so I kept it stock, with new valves and guides. It runs well now, but no obvious improvements.


    Cheers
    Tony
    86' 635
    Bronzit Beige Metallic

  15. #15
    Join Date
    Aug 2010
    Location
    West Nyack, New York
    Posts
    902
    My Cars
    1986 635csi & 1998 740i
    After digesting the info from the 3 posts here, My e28 and Big Coupe--I decided to get the Metric Mechanic Sport Head.
    I already have Jim's tranny that's an excellent box, I would expect his Sport Head would be the ticket I am looking for.
    It's a direct swap because the head is complete. Got his goodies in it from years of experience.

    I'll report my findings after the install.

    Bob V

  16. #16
    Join Date
    Aug 2008
    Location
    Sydney Australa
    Posts
    2,164
    My Cars
    1x633, 1x E3 2 DR Racer
    If you get the chance, do a pre and post dyno. Don't forget the head can only breath as well as the intake manifold, extractors and exhaust flow.
    1977 633 CSi RHD Euro. S38B38 3.8L M5 Transplant. 5 Speed Getrag Dogleg. 3.45 LSD. 390hp, 331lb/ft
    1971 3.0CS E3 2dr Alpina Special Coupe Racer, 300hp, 277lb/ft

  17. #17
    Join Date
    Aug 2010
    Location
    West Nyack, New York
    Posts
    902
    My Cars
    1986 635csi & 1998 740i
    Shipper,

    I asked about porting, polishing the intake and Jim said he's done various tests and the gain
    never justified the costs in his results. I have a Miller MAF with the standard chip.
    I'm trying to find out from them their total advance and fuel setting to see if I have to
    get the War Chip. E-mailed and left phone messages but still no response. Used to be able
    to talk with a tech--Now all are call backs. One cylinder is sucking water so can't do a pre dyno.

    However, at the Glen next year I'll see what rpm's I'll be @ before I brake for the Bus Stop
    and mph before turn one.

  18. #18
    Join Date
    Aug 2008
    Location
    Sydney Australa
    Posts
    2,164
    My Cars
    1x633, 1x E3 2 DR Racer
    You can put a fantastic race head on an engine with a stock manifold (throttle body), extractors and exhaust and see little gain. Porting and polishing will just pick up the last 10% on a face engine. I replaced my exhaust with a single pipe 2.5 inch back when my car ran an M30B32 and it was a fantastic improvement. Team Serlo did it first and their 3 speed 633 was leaving some B35's behind. 6'ers really benefit from free flowing exhaust.

    Here's the logic;

    1. The B35 head is a great flowing head. It generally is not restricting the engine.
    2. The exhaust restricts the engine as it restricts airflow.
    3. The extractors restrict the engine as they restrict airflow.
    4. Same with the intake manifold/throttle body.
    5. Place a new race head and it can only flow as well as the worst of the other three ancillary parts mentioned above. So by default, without a BB throttle body, decent extractors and decent exhaust, your head will be handicapped.

    If you want to get the best out of the head you are buying you need to look at exhaust, extractors and throttle body as well.

    So really, to get the best possible gain, you need to do all three with the head, starting with exhaust.
    Last edited by Shipper; 06-25-2018 at 07:53 PM.
    1977 633 CSi RHD Euro. S38B38 3.8L M5 Transplant. 5 Speed Getrag Dogleg. 3.45 LSD. 390hp, 331lb/ft
    1971 3.0CS E3 2dr Alpina Special Coupe Racer, 300hp, 277lb/ft

  19. #19
    Join Date
    Mar 2009
    Location
    Melbourne, Victoria, Australia
    Posts
    244
    My Cars
    1986 BMw 635 CSi
    Quote Originally Posted by 1986series6 View Post
    After digesting the info from the 3 posts here, My e28 and Big Coupe--I decided to get the Metric Mechanic Sport Head.
    I already have Jim's tranny that's an excellent box, I would expect his Sport Head would be the ticket I am looking for.
    It's a direct swap because the head is complete. Got his goodies in it from years of experience.

    I'll report my findings after the install.

    Bob V
    Bob, you have not confirmed whether your engine is the low compression 8:1 US B34 version, or the high compression Euro B34. I'd be surprised if any head mods would assist much on a lower compression engine.

  20. #20
    Join Date
    Aug 2010
    Location
    West Nyack, New York
    Posts
    902
    My Cars
    1986 635csi & 1998 740i
    It's the 8:1 US version. I can always add a bigger TB and headers later on.

    Or maybe a turbo down the line if I install the turbo head gasket instead of stock one.

    The MM 5 speed will handle the turbo along with the TCD clutch I installed.

    Then for sure I'll have to get Millers turbo chip for the MAF.

    The leak down test confirmed no leaks anywhere except #1 water into cylinder.

  21. #21
    Join Date
    Dec 2005
    Location
    Melbourne, Australia
    Posts
    1,794
    My Cars
    M3evo-Twin Screw/M635csi
    The low comp will still have benifits to improving the VE of head for sure but not yield the same power gains.

    Forced induction does sound a good solution for LHD m30. You could still use abit more compression. Have a look at the cosmetic MLS 027’ head gasket. It will give roughly 40thou gain without shaving the head. If u shave the head also u will get better results with compression but u may need to install clearance cuts in the pistons, install an adjustable cam gear, and alter the chain tensioner. Here’s what I done with m10. I went from 8.5:1 to just on 10:1 with the mls had 030’ head shave. It feels like it’s a bigger capacity engine as with good comp u have benifits everywhere in the rpm range

    BMWs
    74 2002 2.3ltr
    84 E24 M635csi
    86 E23 735i
    94 E34 540i/6 SC 14psi
    97 E36 M3 euro SC

    OTHERS
    02 Landrover D2 td5, 08 Holden Ute 6.0, 11 Audi S5 APR


  22. #22
    Join Date
    Aug 2010
    Location
    West Nyack, New York
    Posts
    902
    My Cars
    1986 635csi & 1998 740i
    Well, I talked to Todd @ TCD and found out that sport head will be no good with a turbo.

    I'm going to cancel the MM sport head and have my head worked to TCD specs to accept his turbo.

    I'll get more bang for the buck with the turbo.

Similar Threads

  1. Head upgrade
    By deejayphilo in forum 1983 - 1991 (E30)
    Replies: 4
    Last Post: 03-15-2010, 03:20 AM
  2. '78 M30 Head Upgrade
    By MattMann in forum 1976 - 1989 (E24)
    Replies: 4
    Last Post: 06-23-2009, 06:18 PM
  3. 95 S50 engine Rebuilt Head & Upgraded WP Cheap!
    By Farvardeen in forum Engines, Performance Parts & Software
    Replies: 21
    Last Post: 09-11-2008, 01:08 PM
  4. 1995 BMW m3 with rebuilt head, upgraded retainers!
    By MreedBMWM3 in forum 3 series & Z Series
    Replies: 1
    Last Post: 08-07-2008, 03:31 PM
  5. head upgrade need help
    By karlow in forum Car Audio & Electronics sponsored by Bavsound
    Replies: 6
    Last Post: 12-19-2006, 09:02 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •